The role of preexisting upper plate strike-slip faults during long-lived (ca. 30 Myr) oblique flat slab subduction, southern Alaska
The role of preexisting upper plate strike-slip faults during long-lived (ca. 30 Myr) oblique flat slab subduction, southern Alaska
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阿拉斯加南部长期（约 30 Myr）倾斜平板俯冲过程中先前存在的上板块走滑断层的作用
DOI：
10.1016/j.epsl.2021.117242
复制
发表时间：
2022
影响因子：
5.3
通讯作者：
O'Sullivan, P.B.
中科院分区：
文献类型：
--
作者：
Waldien, T.S.;Lease, R.O.;Roeske, S.M.;Benowitz, J.A.;O'Sullivan, P.B.
俯冲带的上板块通常通过构造再激活、岩浆弧破裂和前陆盆地反转来响应平板式俯冲。然而，活动走滑断裂在斜向平板俯冲作用下汇聚变形和岩浆作用的作用尚不清楚。在这里，我们给出了来自美国阿拉斯加东部阿拉斯加山脉12个现代集水区的新的碎屑磷灰石裂变径迹(Daft)年龄，以揭示约30 Ma至今的雅库塔特大洋高原倾斜平板俯冲期间，右行德纳利断裂系统如何促进基岩折返和地形生长。此外，940ka(40Ar/39Ar全岩)玄武岩流在空间上与新生代构造有关，局部重新设定了AFT年龄，为东阿拉斯加山脉南侧第四纪火山活动提供了第一个证据。我们将我们的新数据与其他热年代学、年代学和区域地质资料相结合，表明：(1)阿拉斯加南部大部分高地形区自约30 Ma以来经历了快速的基岩冷却和折返；(2)隆起的地势和年轻的冷却在空间上与长期活动的走滑断裂系统有关；(3)与走滑断裂变形有关的地形增长导致盆地系统局部反转和水系重组；(4)倾斜大洋高原俯冲的开始是相同的，弧岩浆活动从走滑活动断裂区的一个区域南移到平板东北缘上方的另一个区域；(5)第四纪火山活动标志着阿拉斯加东部山脉在地球物理成像的平板东北边缘上方的岩浆活动复苏。我们对阿拉斯加南部30 Ma后地质演化的分析表明，在板片压平时活动的走滑断层系统演变成了专注于基岩冷却、岩石折返和地形生长的转压带。
Upper plates of subduction zones commonly respond to flat slab subduction by structural reactivation, magmatic arc disruption, and foreland basin inversion. However, the role of active strike-slip faults in focusing convergent deformation and magmatism in response to oblique flat slab subduction remains less clear. Here, we present new detrital apatite fission-track (dAFT) ages from 12 modern catchments in the eastern Alaska Range, Alaska, USA, to reveal how the dextral Denali fault system has facilitated bedrock exhumation and topographic growth during ca. 30 Ma-to-present oblique flat slab subduction of the Yakutat oceanic plateau. Additionally, a 940 ka (40Ar/39Ar whole rock) basalt flow is spatially associated with Cenozoic structures, locally reset AFT ages and provides the first evidence for Quaternary volcanism along the southern flank of the eastern Alaska Range. We integrate our new data with other thermochronologic, geochronologic, and regional geologic datasets to show that (1) most high topography regions in southern Alaska have undergone rapid bedrock cooling and exhumation since ca. 30 Ma; (2) elevated terrain and young cooling are spatially associated with long-lived active strike-slip fault systems; (3) topographic growth associated with strike-slip fault deformation led to local inversion of basin systems and drainage reorganization; (4) the onset of oblique oceanic plateau subduction is coeval with a southward shift in arc magmatism from one region of active strike-slip faulting to another above the northeastern edge of the flat slab; and (5) Quaternary volcanism marks the revival of magmatism in the eastern Alaska Range above the geophysically imaged northeastern edge of the flat slab. Our analysis of the post-30 Ma geologic evolution of southern Alaska demonstrates that strike-slip fault systems that were active at the time of slab flattening evolved into transpression zones that focused bedrock cooling, rock exhumation, and topographic growth.
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发表时间：
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DOI：
--
发表时间：
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期刊：
影响因子：
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影响因子：
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